ssize_t sendfile - transfering data from one file to another

[ilans11il]

Hi ,
could you plese advise ,I have some problem with the ssize_t sendfile function.

ssize_t sendfile(int out_fd, int in_fd, off_t *offset, size_t count);

the error:

Lesson_4_1A_Home_work.c:84:24: error: expected declaration specifiers or ‘...’ before string constant
Lesson_4_1A_Home_work.c:84:37: error: expected declaration specifiers or ‘...’ before string constant
Lesson_4_1A_Home_work.c:84:63: error: expected declaration specifiers or ‘...’ before ‘strlen’

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/sendfile.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>  //used for exit()
#include <string.h>

#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <error.h>


//prototypes


/*******************************************************************************/
int main()
{
    #define WorkPATH "//home//ilan/Embedded_linux//Lesson-4_IO_Routines_and_File_descriptors//Home_work//My_solution//a.txt"
    #define NewWorkPATH "//home//ilan/Embedded_linux//Lesson-4_IO_Routines_and_File_descriptors//Home_work//My_solution//NEWa.txt"
    int fd,length=0;
    int fdnew;
    int size;
    char read_buffer[80];
    char write_buffer[]="dddddddddddddddddddddddddddddddddd";
    char write_buffernew[]="Hi new file";
    off_t offset = 0;      /* byte offset used by sendfile */
    
    //open the file, if it doesn't exist create it with the following permission access
    fd = open (WorkPATH,/* O_RDONLY */ O_WRONLY  |O_CREAT,0600);
    if (fd == -1) 
    {
        /* The open failed. Print an error message and exit. */
        printf("error opening file: \n");
        exit(-1);
    }
    
    fdnew = open (NewWorkPATH,/* O_RDONLY */ O_WRONLY  |O_CREAT,0600);
    if (fdnew == -1) 
    {
        /* The open failed. Print an error message and exit. */
        printf("error opening file: \n");
        exit(-1);
    }
    
    /* Read the size of the data in the  file. */
    //Use the systems calls in order to read from $path via read only permissions
    read (fd, read_buffer, sizeof (read_buffer));
    
    //Try to write to it ,with the same read only permissions
     write (fd, write_buffer, strlen (write_buffer));
    
        printf("The file - a.txt - Content is: \n");
            system("cat a.txt\n");    
    // Close the file descriptor, 
    close (fd);
         
      ssize_t sendfile(NewWorkPATH, WorkPATH, off_t *offset,  strlen(write_buffer));
    
    
    // read (fd, read_buffer, sizeof (read_buffer));
    // write (fd, write_buffernew, strlen (write_buffer));
         printf("The file -NEWa.txt - Content is: \n");
            system("cat NEWa.txt\n");    
}

[grumpy]

Sorry, but given this site's policy about homework (at this link) I'm not inclined to be sympathetic to a transparent attempt to snaffle some code from someone else instead of actually doing your homework, after which you have attempted to make a change by guesswork, with negligible understanding of the programming language, let alone what the code does.

[Salem]

> #define WorkPATH "//home//ilan/Embedded_linux//Lesson-4_IO_Routines_and_File_descriptors//Home_work//My_solution//a.txt"
> #define NewWorkPATH "//home//ilan/Embedded_linux//Lesson-4_IO_Routines_and_File_descriptors//Home_work//My_solution//NEWa.txt"
What's with all the // in the pathnames?
A single / suffices.

Perhaps you're thinking of that other OS, where you have to write "\\path\\to\\file.txt"

> ssize_t sendfile(NewWorkPATH, WorkPATH, off_t *offset, strlen(write_buffer));
It seems you stopped editing the function prototype half-way through, then forgot what you were doing.
At a guess
ssize_t result = sendfile(NewWorkPATH, WorkPATH, &offset, strlen(write_buffer));

[grumpy]

At a guess
ssize_t result = sendfile(NewWorkPATH, WorkPATH, &offset, strlen(write_buffer));

... except that the two arguments to sendfile() are of type int, not type char *. However, look at what preceding code does with open() .....